中文摘要：

陆地生态系统碳收支仍然是当前全球气候变化研究的重要内容,青藏高原作为全球气候变化的敏感区,使青藏高原草地生态系统在区域碳收支平衡中占有主导地位,但研究方法等不同使得碳收支估算结果存在很大的不确定性。气候变暖在一定程度上提高了高寒草地生态系统的植被初级生产力和生物量,由此补偿了气候变暖导致的土壤有机碳分解释量,使青藏高原草地植被仍然发挥着碳汇的功能。而人类放牧活动对草地生态系统的影响较为复杂。因此,如何区分气候变化和人类活动对生态系统的影响机制,定量评价未来气候变化和人类活动影响下,青藏高原生态系统碳源/汇格局的可能变化,是一个非常重要的研究方向,也是一个极大的挑战。

英文摘要：

Terrestrial ecosystem carbon budget is a hot topic in the research on global climate change.The grassland of Qinghai-Tibet Plateau,which is sensitive to climate change,plays an important role in the regional carbon balance.However,there is great uncertainty in the estimation on the spatial-temporal pattern of carbon budget due to different methods and some other reasons.To some extent,climate warming results in the increase of vegetation primary productivity and biomass in the alpine meadow ecosystem,which may compensate the decomposition release of soil organic carbon.Hence,the Qinghai-Tibet Plateau grassland still functions as a carbon sink.The effects of human activities,such as overgrazing,on grassland ecosystems are very complex.Therefore,under the impacts of future climate change and human activities,how to distinguish the influence of climate change from that of human activities on ecosystems,and how to quantitatively assess carbon source / sink pattern,are a very interesting research field,but also a great challenge,especially on the plateau.